Linear polyesters from p, p&#39;-sulfonyl dibenzoic acid plus aliphatic dibasic straight chain acids condensed with a glycol



United States Patent LINEAR POLYESTERS FROM p,p-SULFONYL DI- BENZOIC ACID PLUS ALIPHATIC DIBASIC STRAIGHT CHAIN ACIDS CONDENSED WITH A GLYCOL John R. Caldwell, Kingsporn Tenm, assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application October 3, 1952, Serial N0. 313,063

24 Claims. (Cl. 260-75) This application relates to valuable linear polyesters prepared by condensing a p, p'-sulfonyl dibenzoic diester in conjunction with an aliphatic straight-chain dibasic acid diester containing at least four carbon atoms with a polymethylene glycol and/or an aliphatic ether glycol.

It is an object of this invention to provide novel inter- It is another object to polyesters as described herein. provide a process as described herein for preparing valuable interpolyesters. Other objects will become apparent hereinafter.

This application is a continuation-in-part of my c0- pending application, Serial No. 143,594, filed February 10, 1950, now U. S. Patent No. 2,614,120, dated October 14, 1952. In that application sulfonyl dibenzoic' acid is called his (dicarboxydiphenylsulfone).

Highly polymeric esters of terephthalic acid and various glycols, for example, ethylene glycol, trimethylene glycol, hexamethylene glycol, etc., are well known, and have been used in the preparation of linear, highly polymeric polyesters having properties including that of being capable of being formed into useful filaments, fibers and the like, and having high melting points and a low degree of solubility in organic solvents. Linear polyesters prepared from other aromatic dicarboxylic acids have also been described in the prior art and contemporary art.

interpolyesters of terephthalic acid and other dibasic acids condensed with dihydroxy compounds have also been described.

None of the polyesters known in the prior art are easily prepared without high cost. Moreover, they do not possess the herein-described highly advantageous properties which render them especially suitable for processing by injection molding and extrusion methods. Furthermore, the known polyesters do not possess the low modulus of elasticity resulting in high resiliencyand reversible extensibility possessed by the interpolyesters described herein.

It has now been found that p, p-sulr"onyl dibenzoic acid or its esters or its acid chloride plus an aliphatic straightchain dibasic acid or a diester thereof can be condensed with a polymethylene glycol and/or an aliphatic ether glycol to produce a new kind of linear interpolyester having highly'valuable properties which are superior to those of the linear polyesters described in the prior art. Thus, my new interpolyesters can be prepared having a relatively wide softening range and good flow characteristics whereby they are quite valuable for the production of shaped objects by injection molding or extrusion methods. These novel interpolyesters can be prepared so as to soften at temperatures which are above about 180 C. Useful interpolyesters can also beprepared which soften at lower temperatures. 7

The novel interpolyesters described herein are quite useful in the making of electrical insulation.

These novel interpolyesters can be prepared so as to have especially valuable properties when formed into fibers by melt spinning methodsfollowed by drawing.

. 2 o These fibers can be prepared so' as to have a reversible extensibility of about 30% or more.

The modulus of elasticity of these interpolyesters is unusually low compared to known polyesters; accordingly, these interpolyesters are quite rubbery and resilient. They are highly valuable where a high degree of elastic recovery is desirable, e. g., gaskets, packing, resilient elastic fabrics, flexible tubing, elastic clothing, etc. Although interpolyesters can be prepared which soften at -200 C. or higher, many valuable products can be produced which soften at lower temperatures.

My novel interpolyesters may contain as constituents thereof small percentages of the m,m and/or the m,p

isomers of the p,p-sulfonyl dibenzoic compound without significant deleterious efiect on the properties of these interpolyesters. In fact, when the interpolyester is to be employed for purposes other than for making fibers, substantial quantities of these isomers can be employed with some advantageous results, especially as regards increas ing the softening temperature range. v

Two of the outstanding qualities of the interpolyesters of this invention are their excellent dimensional stability and low degree of water absorptivity. This results in superior resistance to dimensional change despite changes in atmospheric humidity or immersion in aqueous solutrons.

The interpolyesters of this invention have melting points which are up was much as or more than 50 C. higher than corresponding interpolyesters prepared from dibasio acidic compound combinations described in the prior art.v This characteristic results in a much greater effective range of utility for these new interpolyesters, for instance, gaskets can be prepared for employment in equipment operating at higher temperatures, fibers can be made which withstand higher ironing temperatures when fabrics are prepared from yarns incorporating these fibers, etc.

One embodiment of this invention relates to a process for preparing an interpolyester comprising (A) condensing about 10 mole proportions of a sulfonyl dibenzoic compound having the formula:

wherein it represents a positive integer of from 2 to 18, inclusive, and R8 and R9 each represents a substituent selected from the group consisting of an omega hydroxyalkyl radical containing from 2 to 12 carbon atoms and an alkyl radical containing from 1 to 6 carbon atoms, (B) with a dioxy compound selected from the group consisting of those compounds having the following formu las: I

wherein p represents a positive integer of from 2 to 12, R5 and Re each represents a substituent selected from the group consisting of a hydrogen atom and an acyl radical containing from 2 to 4 carbon atoms, R7 represents an alkylene radical containing from 2 to 4 carbon atoms and q represents a positive integer of from 1 to 10 Patented May 1, 1956 inclusive, the dioxy compound being employed in such a proportion that there is at least an equivalent amount of substituents in proportion to the carbalkoxy substituents in the overall combination of the diesters and the dioxy compounds, (C) in the presence of a condensing agent selected from the group consisting of the alkali metals, the alkaline earth metals, the oxides of these two groups of metals, the alkoxides containing from 1 to 6 carbon atoms of these two groups of metals, the carbonates and borates of these two groups of metals, lead oxide, and compounds having the following formulas:

wherein M represents an alkali metal, M represents an alkaline earth metal selected from the group consisting of magnesium, calcium and strontium, R represents an alkyl group containing from 1 to 6 carbon atoms, R, R" and R' each represents a member of the group consisting of R and an aryl group of the benzene series containing from 6 to 9 carbon atoms and Hal represents a halogen atom, (D) at an elevated temperature, (E) the condensation being conducted in an inert atmosphere, and (F) the latter part of the condensation being conducted at a very low pressure of the inert atmosphere.

Advantageously, the dioxy compound is employed in such a proportion that there are from about 1.2 to about 3 substituents in proportion to the carbalkoxy substituents in the overall combination of the diesters and the dioxy compounds. Advantageously, the low pressure defined under (F) is less than about 15 mm. of Hg pressure. Advantageously, the elevated temperature employed during the earlier part of the condensation is from about 150 to about 220 C. Advantageously, the dioxy compound is a glycol having the formula:

wherein p is defined under (B) above.

The dioxy compounds defined above may not actually contain any free hydroxy radicals since they may be in esterified form as indicated by the formulas given. However, these hydroxy or substituted hydroxy radicals are referred to generically as hydroxy radicals or substituents. The dioxy compounds which can be employed in accordance with this invention are most advantageously dihydroxy compounds, such compounds will hereinafter he referred to as dihydroxy compounds although it is to be understood that dioxy compounds of the type described above are intended to be covered by this term. Each diester is considered as containing two carbalkoxy radicals as that term is employed in the definition of the process as described above since R1 and R4 may be alkyl radicals, omega-hydroxyalkyl radicals or fl-hydroxyalkyl radicals and Rs and R9 may be alkyl radicals or omegahydroxyalkyl radicals. Even when the process is preceded by the preliminary step described below employing free acids, the term carbalkoxy radicals in the description of the process is intended to encompass such free carboxy radicals.

Furthermore, this invention covers a process as defined above wherein either or both of the sulfonyl dibenzoic acid diester and the aliphatic dibasic acid diester is/ are formed by a preliminary step comprising condensing free p,p-sulfonyl dibenzoic and/or free aliphatic dibasic acid with a dihydroxy compound which is defined under (B) and is employed in the proportions set forth under (B), at an elevated temperature, after which prellminary step the condensing agent which is defined under (C) is added and the condensation is completed as defined under (D), (E) and (F). Advantageously the elevated temperature employed during the preliminary step is substantially that at which reflux conditions subsist; however, higher and lower temperatures can also be employed. Advantageously, as indicated above the dihydroxy compound is employed in such a proportion that there are from about 1.2 to about 3 hydroxy substituents in proportion to the carboxy and carbalkoxy substituents in the overall combination of the diacids, diesters, and dihydroxy compounds.

As indicated above, the interpolyesters described herein have relatively wide softening ranges and good flow properties. In this respect, they difler from most types of high-melting linear polyesters, such as polyethylene terephthalate, which possess sharp melting points. Thus. these modified polyesters of sulfonyl dibenzoic acid soften over a sufficiently wide temperature range that they can be advantageously employed in the production of shaped objects by injection molding and extrusion methods.

The alkylene glycols which can be employed to form highly polymeric linear polyesters are straight-chain alkane diols, viz. polymethylene glycols, wherein the hydroxy radicals are positioned at the two ends of the alkylene chain. Examples of such glycols include ethylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,6- hexylene glycol, 1,10-decamethylene glycol, 1,12-dodecametliyl glycol, etc. As indicated above, mono or diesters of these glycols can also be employed. Thus. the acetates, propionates and butyrates are examples of such esters. The defined ether glycols can be employed either in lieu of the polymethylene glycols or in conjunction therewith as modifiers. Mixtures of alkylenc glycols or ether glycols can also be employed. Examples of ether glycols include diethylene glycol, triethylene glycol, tetraethylene glycol, bis (4-hydroxybutyl) ether, bis (3-hydroxypropyl) ether, etc. When mixtures of alkylene glycols and ether glycols are employed, it is generally preferable to employ a major proportion of the alkylene glycol in order to obtain higher melting linear polyesters. The high melting characteristic also is dependent upon the amount of straight chain aliphatic dibasic acid present in the interpolyester, the chain length of this aliphatic acid and the chain length of the glycol employed. Higher proportions of the aliphatic acid low er the melting and softening temperatures of the inter polyesters. This effect is also produced when a longer chain-length aliphatic acid is employed in the same proportions as a shorter chain length aliphatic acid. The same eifect'is created by employing a longer chain (higher carbon content) alkylene glycol. For example, when a 10-12 carbon atom glycol is employed, the amount of aliphatic ether glycol used should preferably be not more than about 1020 mole per cent; whereas, when a 2-4 carbon atom glycol is employed the amount of ether glycol can be as high as about 50 mole per cent of the total quantity of dihydroxy compounds employed.

When no ether glycol is employed, it is preferred to employ polymethylene glycols containing from 4 to 8 carbon atoms; this is especially important when the aliphatic acid has a rather short chain length, the proportion thereof is relatively low and the polymethylenc glycol also has a short chain length (e. g., ethylene and trimethylene glycol) under which conditions the mole ratio of the p,p' sulfonyl dibenzoic ester to the aliphatic diester should be from 10:10 to 10:30 since the melting point of the interpolyester produced might otherwise be above 300 C. whereby decomposition would take place whenever the polyester was melted or softened.

Valuable fibers having high melting temperatures can be prepared by incorporating very little, preferably none, of an aliphaticether glycol and less than 15 mole percent of the aliphatic dibasic acid (of the type describedabove) into an interpolyester containing about 85 90 mole percent of the p,p'-sulfonyl dibenzoic constituent. It is particularly advantageous to employ a polymethylene glycol containing from 5 to 8 carbon atoms and an aliphatic diester containing from 4 to carbon atoms in the acid constituent when it is desired to obtain fibers having a pronounced degree of elastic extensibility. For general molding and extrusion purposes, glycols containing from 2 to 6 or 8 carbon atoms and the 4 to 10 carbon atom acid diesters are usually to be preferred. However, on the other hand, valuable interpolyesters can be prepared employing aliphatic ether glycols without any alkylene glycol although the product obtained will not be suitable for forming useful fibers.

The catalytic condensing agents which can be employed have been described above. From about 0.005% to about 0.2% of such catalysts based on the weight of the reactants being condensed can be employed. Higher or lower percentages can also be employed. Generally, from about 0.01% to about 0.06% of the catalytic condensing agent can be advantageously employed based on the weight of the various diesters being condensed.

The temperature at which polyestenification can be conducted is dependent upon the specific reactants involved in any given reaction. In general, the reaction mixture can be heated at from about 150 to about 220 C. for from approximately two to three hours in an inertatmosphere (e. g. nitrogen or hydrogen); the mixture can then be heated at from about 225 240 to about 2803 10 C. in the same atmosphere for approximately 1 to 2 hours. Finally, the pressure can be greatly reduced to form a vacuum (less than about mm. of Hg pressure but preferably on the order of less than 5 mm. of Hg pressure) while the temperature is maintained in the same range (225 3l0 C.); these conditions are advantageously maintained for approximately 4 to 6 additional hours. This final phase is advantageously carried .out with good agitation under the high vacuum in order to facilitate the escape of volatile products from the highly viscous melt. The conditions can be varied-considerably depending upon the degree of polyesterification desired, the ultimate properties sought, the stability of the polyester being produced, and the use for which the product is intended. Thus, the extent of the substitution of the sulfonyl dibenzoic diesters with the esters of additional modifying acid necessitates variations in these conditions of temperature, pressure and time periods required. The employment of the novel catalytic condensing agents listed hereinabove results in better products being preparedin much less time than is possible when the catalysts of the prior art are employed.

It has been found that the type of catalyst used has an important bearing upon the properties of the final product. Although most of the catalysts cited in the prior art may be used, it has been found that certain novel catalysts give superior results. The aluminum and titanium alkoxide complexes described in copending applications filed on even date herewith are especially valuable for the preparation of the polyesters described here. Moreover, novel tin catalysts have also been found to be especially eifective. See Caldwell Serial No. 313,072, Serial No. 313,078, Caldwell and Reynolds Serial No. 313,077, Wellman and Caldwell Serial No. 313,074, Serial No. 313,075, and Serial No. 313,076, and Wellman Serial No. 313,073 for a description of especially advantageous catalytic condensing agents.

The reaction can be carried out in the presence or absence of a solvent. Inert, high boiling compounds, such as diphenyl ether, diphenyl, mixed tolyl sulfones, chlorinated naphthalene, chlorinated diphenyl, dimethyl sulfolane, etc. can be used as the reaction medium.

It is important to exclude oxygen and moisture at all stages of the condensation reaction. Inert atmospheres which can be advantageously employed include nitrogen, hydrogen, helium, etc. Substantially anhydrous reactants essential, especially if any water is removed in the earlier stages of the condensation. V

As indicated above, the acidic constituents of the interpolyesters are employed in the form of their diesters. The omega-hydroxyalkyl diesters can be prepared as described above by heating a polymethylene glycol (or an aliphatic ether glycol), with the free acid, preferably employing an excess of the glycol. The beta-hydroxyalkyl diesters can be prepared as described in my parent application employing an alkylene oxide. The acid chlorides can be employed in some cases although the conditions involved are generally substantially difierent.

Examples of the various diesters which can be employed in accordance with the process of this invention include the ethyl, propyl, n-butyl, sec-butyl, isopropyl, sec-amyl, n-hexyl, IO-hydroxydecyl, S-hydroxyamyl, 12-hydroxydodecyl, Z-hydroxyethyl, etc. diesters of either p,p'-sulfonyl dibenzoic acid, or any of the aliphatic straight chain dibasic acids of the type describedabove. When the novel catalytic condensing agents described hereinabove and in copending applications referred to herein are employed, the simple alkyl esters of these various dibasic acids can be advantageously employed, whereas if the catalysts known to the prior art are employed, the condensation will not proceed as rapidly or as effectively although satisfactory results can be obtained.

The advantageous ratio of p,p'sulfonyldibenzoic diester to the modifying aliphatic dibasic acid diester will depend upon the type of product desired. As the mole percent of the modifying acid in the polyester is increased, the melting point of the product is lowered. When short chain glycols such as ethylene glycol and tetramethylene glycol are used, it is usually preferable to employ from 1 to 3 moles of the modifying acid diester for each mole of p,p-sulfonyldibenzoic diester in order to keep the melting point of the product below its decomposition temperature. When higher glycols such as pentamethylene, hexamethylene, and octamethylene glycol are used, from about 1 to about 7-8 moles of the aliphatic dibasic acid diester can be employed for each ten moles of p,p'-sulfonyl dibenzoic acid.

As indicated hereinabove, some of the isomers of p,p-sulfonyl dibenzoic acid can be employed under some circumstances with resultant lowering of the melting or softening temperatures but with a probable increase in the softening range of temperatures. The same efliect is produced when homologs of p,p'-sulfonyl dibenzoic acid are incorporated into the materials being condensed to prepare these interpolyesters. If homologs are employed they are product is not intended to be used in the preparation of The products of this invention are linear interpolyesters which possess favorable flow characteristics over a temperature differential or range of about 5 to 20 C., a low modulus of elasticity and which containin the interpolyester configuration a ratio of about 10 of one of the following repeating units:

to each 1 to about 30 of one of the following repeating units:

--O-OC- CH2) CO-O-( CH2 11 wherein p and t are defined above.

When the ratio of the repeating units is, respectively, from about 10:1 to about 10:2 these interpolyesters are 7 capable. of'bejng spuninto fibers which can be drawn to from. about 3 to 6 times their originally spunlength thereby developing strong, elastic properties distinguished by ahigh degreeof reversible extensibility.

The above described interpolyesters can also have either one. or both of the two types of repeating units depicted above replaced entirely or in part, respectively, by one of the following repeating units:

wherein q and R7 are defined above.

In the examples given below, the hot bar sticking temperature is referred to in several instances. The hot bar sticking test can be briefly described as follows:

A polyester fiber is placed on the flat surface of a heated bar-and a weight of 100 grams is applied to the fiber along a distance of /8 inch of the fiber length. The contact surface of this weight has a coating of polytetrafiuoroethylene which acts as a thermal insulator. The film is allowed to remain in contact with the bar under this weight for one minute. The minimum temperature at which the fiberadheres to the hot bar under these conditions is the sticking temperature as that term is employed in the examples given herein.

This invention can be further illustrated by the following examples; in addition to these examples it is apparent that other variations and modifications thereof can be adapted to obtain similar results:

Example I.Ethyl succinate and tetrametlzylene glycol Four hundred and twenty grams (1.0 mol) p,p'-sulfonyl dibenzoic acid dibutyl ester, 260 g. (1.5 mol) diethyl succinate, and 450 g. (5.0 mols) tetramethylene glycol were placed in a reaction vessel equipped with a stirrer, a short distillation column, and an inlet tube for purified nitrogen. Ten cc. of butyl alcohol containing 0.25 g. sodium titanium butoxide was added as a catalyst, and the mixture was heated at 200-210 C. with stirring. After one to two hours, the evolution of ethyl and butyl alcohols ceased, showing that theester interchange was practically complete. The temperature was then raised to 270-275 C. and held for 20-30 minutes. A vacuum of 0.5 to 1.0 mm. was then applied, and the heating and stirring were continued for 2 /2 to 3 hours. A colorless product having an inherent viscosity of 0.90 to 1.1 in 60% phenol40% tetrachlorethane was obtained. This polyester can be injection molded at about 250 C. to give colorless products that are very tough and strong. They retain their shape even when subjected to a temperature of 180-190 C. Rods, tubes, sheets, and profile shapes can be extruded by the usual methods. The polyester is especially suitable for conversion into fibers by melt spinning methods. After drafting and heat-treating, the fibers have a strength of 3.0 grams per denier and a reversible elongation of 20-25%. They are valuable for the production of elastic garments.

Example II.--Methyl sebacatc and ethylene glycol Four hundred and twenty grams (1.0 mol) p,p'-sulfonyl dibenzoic acid dibutyl ester, 300 grams (1.3 mol) methyl sebacate, and 250 g. (4.0 mols) ethylene glycol were placed in a reaction vessel equipped with a stirrer, short distillation column, and an inlet for purified hydrogcn. Methyl magnesium iodide (0.2 g.) dissolved in 10 cc. butyl ether was added as a catalyst. The mixture was stirred at 180-190 C. for 6 hours to remove methyl and butyl alcohols as they were formed by ester interchange. The temperature was then raised to 285290 C. during a period of 1 hour. A vacuum of 0.5 to 1.0 mm. was applied for 3 to 4 hours while the temperature was maintained at 285-290 C. The product; obtained was colorless and has an inherent viscosity of 0.7 111.60% phenol-40% tetrachlorethane. The polyester can be moldedin an injection press to give shaped objects that have a very high impact strength. They retain-their shape up to a temperature of 220-230 C. They also show good flexibility at temperatures of 30 to -40 C. This polyester is especially valuable for extrusion as tubes, sheets, or rods. Fibers can be spun from the polyester by melt-extrusion methods. After drafting and heat-treating, the fibers have a strength of 2.5 to 3.0 grams per denier and a reversible elongation of 20 to 50%.

Example Il1.Ethyl azelate and tetmmeihylene glycol Four hundred twenty grams (1.0 mol) p,p'-sulfonyl dibenzoic acid dibutyl ester, 366 g. 1.5 mol) ethyl azelate, and 330 g. butanediol-IA were placed in a reaction vessel as described in Example I. A solution of 0.2 g. lithium titanium butoxide in 15 cc. butyl alcohol was added. The mixture was stirred at l-200 C. in an atmosphere of purified nitrogen. A mixture of ethyl and butyl alcohol distill oil. The evolution of alcohol practically stopped after 2 hours, and the temperature was raised to 260270 where it was held for 30 minutes. A vacuum of 0.5 to 1.0 mm. of Hg was applied and the reaction mixture was stirred at 260270 for 3.5 to 5 hours. The product obtained was colorless and has an inherent viscosity of 0.85 in 60% phenol-40% tetrachlorethane. The polyester can be converted to films, tubes, sheets, rods, etc., by extrusion methods. Fibers can be made by melt-spinning. The polymer is especially useful for injection molding. It is useful as an insulator for wire and other electrical equipment.

Example I V.Ethyl succinate and pentanzethylene glycol Three hundred and seventy-two grams (1.0 mol) p,p'- sulfonyl dibenzoic acid diethyl ester, g. (1.0 mol) diethyl succinate, and 400 g. pentanediol-l,5 were placed in a reaction vessel as described in Example 1. Ten cc. of ethyl alcohol containing 0.40 g. sodium aluminum ethoxide was added as a catalyst. The mixture was heated and stirred at 200210 C. in an atmosphere of purified hydrogen. Ethyl alcohol distilled rapidly from the reaction mixture and the ester interchange was practically complete in 2 hours. The temperature was then raised to 250260 C. where it was held for one hour. A vacuum of 1 to 2 mm. of Hg was applied and the melt stirred at 250260 for 3 to 3 /2 hours. The product obtained has an inherent viscosity of 0.8 to 0.9 in 60% phenol- 40% tetrachlorethane solution. The polyester can be extruded as film, rods, tubes, or sheets. It can be injection molded to give products that retain their shape up to 170180 C. Fibers can be spun by the usual meltspinning methods.

Example V.Metlzyl adipate and lzexamethylene glycol Three hundred and seventy-two grams (1.0 mol) p,psulfonyl dibenzoic acid diethyl ester, 260 g. (1.5 mol) dimethyl adipate, and 480 g. hexarnethylene glycol were placed in a reaction vessel equipped as described in Example I. A solution of 0.2 g. lithium ethoxide in 20 cc. ethyl alcohol and a piece of magnesium ribbon weighing about 0.1 g. were added as the catalyst. The mixture was stirred at 200 C. in an atmosphere of purified nitrogen until most of the methyl and ethyl alcohol had distilled. The temperature was then raised to 220- 230 and held for one hour. A vacuum of 1 to 2 mm. was applied for 4 hours. The product obtained has an intrinsic viscosity of 0.5 to 0.6. It is useful as a molding plastic and can also be extruded in the form of rods, tubes, films, etc. It softens at 120-130" C.

Example VI.-Eth.yl glutarate and tetramctlzylene glycol The procedure of Example I was repeated exactly except that ethyl glutarate was employed instead of ethyl succinate. The interpolyester obtained has similar properties except that the softening and melting temperatures were a few degrees lower.

Example VIL-Ethyl succinate and decamethylene glycol Example VIIL-Methyl sebacate and hexamethylene glycol One mol of methyl sebacate, 4 mols of p,p-sulfonyl dibenzoic acid, butyl ester, and 7 mols 1,6-hexanediol were placed in a vessel as described in Example I. Fivehundredths percent sodium aluminum ethoxide was added, based on the weightof the two esters. A heating schedule similar to that given in Example I was followed. The product obtained is very tough and rubbery. It has an inherent viscosity of 0.80 in a solvent of 60% phenol- 40% tetrachlorethane. Fibers pulled from the melt show a rubbery elastic elongation of 30-40 percent. This product is also useful as a molding plastic.

Example IX.-Methyl sebacate and hexamethylene glycol Example X.Methyl sebacate and hexamethylene glycol One mol of methyl sebacate, 4 mols of p,p'-sulfonyl dibenzoic acid, butyl ester, and 7 mols 1,6-hexanediol were placed in a vessel as described in Example I. Five-hundredths percent K2(Ti(OC2H5)s) was added, based on the weight of the two esters. A heating schedule similar to that given in Example I was followed. The product obtained is very tough and rubbery. It has an inherent viscosity of 0.80 in a solvent of 60% phenol-40% tertachlorethane. Fibers pulled from the melt show a rubbery elastic elongation of 30-40 percent. This product is also useful as a molding plastic.

Example XI.Methyl sebacate and hexamethylene glycol One mol of methyl sebacate, 4 mols of p,p'-sulfonyl dibenzoic acid, butyl ester, and 7 mols 1,6-hexanediol were placed in a vessel as described in Example I. Five-hundredths percent Ca(Ti(OC2H5)s)2 was added, based on the weight of the two esters. A heating schedule similar to that given in Example I was followed. The product obtained is very tough and rubbery. It has an inherent viscosity of 0.80 in a solvent of 60% phenol-40% tetra-- chlorethane. Fibers pulled from the melt show a rubbery elastic elongation of 30-40%. This product is also use ful as a molding plastic.

Example XIIMethyl sebacate and hexamethylene glycol One mol of methyl sebacate, 4 mols of p,p'- sulfonyl.

dibenzoic acid, butyl ester, and 7 mols 1,6-hexanediol were placed in a'vessel as described in ExampleI. Fivehundredths percent was added, based (mu-1e weight of the two esters. A

heating schedule similar to that given in Example I- was then raised to 280-290 C. for 1 hour longer.

10 followed. The product obtained is very tough and rubbery. It has an inherent viscosity of 0.80 in a solvent of 60% phenol-40% tetrachlorethane. Fibers pulled from the melt show a rubbery elastic elongation of 30-40%. This product is also useful as a molding plastic.

Example XIIl.Methyl sebacate and hexamethylene glycol One mol of methyl sebacate, 4 mols of p,p-sulfonyl dibenzoic acid, butyl ester, and 7 mols 1,6-hexanediol were placed in a vessel as described in Example I. Fivehundredths percent Ti(OC3H'z)4 was added, based on the weight of the two esters. A heating schedule similar to that given in Example I was followed. The product obtained is very tough and rubbery. It has an inherent viscosity of 0.80 in a solvent of 60% phenol-40% tetrachlorethane. Fibers pulled from the melt show a rubbery elastic elongation of 30-40%. This product is also useful as a molding plastic.

Example XI V.Methyl sebacate and hexamethylene glycol obtained is very tough and rubbery. It has an inherent. viscosity of 0.80 in a solvent of 60% phenol-40% tetra-- chlorethane. Fibers pulled from the melt show a rubbery- This product is also use-- elastic elongation of 30-40%; ful as a molding plastic.

Example XV.Methyl sebacate and ethylene glycol A catalyst was prepared by reacting 20 grams of magnesium metal with cc. ethyl iodide in 250 cc. dry diethyl ether. Two-tenths of one cc. of this catalyst were added to a mixture of 83.6 g. of the butyl ester of p,p'-sulfonyl dibenzoic acid, 46 g. dimethyl sebacate and g. ethylene glycol. The mixture was heated under hydrogen with stirring at C. for 3 hours at the end of which period the theoretical amounts of alcohols had been evolved. It was then heated at 295 C. and under hydrogen for /2 hour. It was finally heated in a vacuum of less than one millimeter of mercury for 2 hours. The product obtained was a pure white, exceedingly tough, elastic interpolyester with an intrinsic viscosity of 0.5 in 60% phenol-40% tetrachlorethane solution.

Example XVI.Adipic acid and ethylene glycol derivative added. This mixture was heated at 220-230 C. for 3' The temperature was The pressure was then reduced to 0.1 mm. of Hg pressure, the temperature was increased to 280 290? C. and these conditions were maintained for 3 more hours. The resulting product was a hard, tough, resilient resin that softens at 200 -210 C. It is useful as a molding plastic.

Example XVI illustrates that the free acid can be employed in lieu of the diester of the aliphatic dibasic acid. However, it is generally more advantageous to employ a diester such as methyl adipate in preparing an interpolyester. Example XVI also illustrates the employment of a ,B-hydroxyalkyl diester of p,p'-sulfonyl dibenzoic acid. When the B-hydroxyethyl diester is employed, no glycol need be employed since it is present in the form hours in a stream of nitrogen.

of a derivative i. e., a monoester of ethylene glycol. Howpresent. y I a J 11 Example XVII.--Ethyl octadecane-L18-di0ate and ethylene glycol One gram mole of the diethyl ester of p,p'-sulfonyl dibenzoic acid, 0.8 gram mole of the diethyl ester of 1,18-octadecanedioic acid and 3.5 gram moles of ethylene glycol were placed in a reaction vessel equipped as described in Example I. Ten cc. of ethyl alcohol containing 0.40 gram of sodium aluminum ethoxide was added as-a catalyst. The mixture was heated and stirred at 185-l95 C. in an atmosphere of purified nitrogen. Ethyl alcohol distilled off and when its evolution had come to a stop the temperature Was raised to 240-260 C. whereit was held for 45 minutes. A vacuum of 0.2 mm. of Hg pressure was then applied and the melt stirred for 4 hours. The interpolyester obtained was tough, rcsilient and useful as a molding resin and for other purposes. This interpolyester can be formed into products which retain their shape at temperatures in excess of 125130 C.

Example XVIII.Methyl adipate and hexamethylene glycol The procedure described in Example V was repeated exactly except that 0.5 g. Sr(OCHs)2 dissolved in methyl alcohol was employed as the catalyst. A product was obtained which was practically identical to the interpolyester produced in Example V. Similar results can be obtained using as the catalyst K, Ca, LizCOa, CaBOz, PbO (litharge), etc. Such catalysts can also be employed in the processes described in the other examples after making suitable allowance for the differences in the reaction rates inherent in the change of the catalyst.

What I claim is:

1. A process for preparing a linear polyester softening at above 180200 C. comprising (A) condensing about 10 mole proportions of a p,p'-sulfonyl dibenzoic diester having the formula:

wherein R1 and R4 each represents a substituent selected from the group consisting of a fl-hydroxyalkyl radical containing from 2 to 4 carbon atoms, an omega-hydroxyalkyl radical containing from 3 to 12 carbon atoms and an alkyl radical containing from 1 to 6 carbon atoms, plus from about 1 up to 7 mole proportions of an aliphatic diester selected from the group consisting of those having the following formulas:

wherein t represents a positive integer of from 2 to 18, inclusive, and Rs and R9 each represents a substituent selected from the group consistingof an omega-hydroxyalkyl radical containing from 2 to 12 carbon atoms and an alkyl radical containing from 1 to 6 carbon atoms, (B) with a dioxy compound selected from the group con sisting of those compounds having the following formulas:

wherein 2 represents a positive integer of from 2 to 12, R and Re each represents a substituent selected from the group consisting of a hydrogen atom and an acyl radical containing from 2 to 4 carbon atoms, R7 represents an alkylene radical containing from 2 to 4 carbon atoms and q represents a positive integer of from 1 to inelusive, the dioxy compound being employed in such a porportion that there is at least an equivalent amount of oxy substituents in proportion to the carbalkoxy substituents in the overall combination of the diesters and the dioxy compound, (C) in the presence of a condensing: agent selected from the group consisting of the alkali metals, the alkaline earth metals, the oxides of these two groups of metals, the alkoxides containing from 1 to 6 carbon atoms of these two groups of metals, the carbonates and borates of these two groups of metals and lead oxide, (D) at an elevated temperature, (E) the condensation being conducted in an inert atmosphere, and (F) the latter part of the condensation being conducted at a very low pressure of the inert atmosphere, said process encompassingthe condensation of only those compounds referred to in (A) and (B) hereinabove.

2. A process as defined in claim 1 wherein the elevated temperature is increased gradually during the course of the condensation up to a temperature of from about 225 to about 310 C.

3. A process as defined in claim 2 wherein the condensing, agent is employed in an amount of from about 0.005% to about 0.2% based on the weight of the diesters employed.

4. A process as defined in claim 3 wherein the dioxy compound is employed in such a proportion that there are from about 1.2 to about 3 oxy substituents in proportion to the carbalkoxy substituents in the overall combination of the diesters and the dioxy compounds.

5. A process as defined in claim 4 wherein the elevated temperature employed during the earlier part of the condensation is from about to about 220 C. and the low pressure defined under (F) is less than about 15 mm. of Hg pressure.

6. A process as defined in claim 5 wherein all materials employed in the process are substantially anhydrous.

7. A process as defined in claim 6 wherein the dioxy compound has the formula:

wherein p is defined under (B).

8. A process as defined in claim 7 wherein the aliphatic diester is ethyl succinate and the dihydroxy compound is pentamethylene glycol.

9. A process as defined in claim 7 wherein the aliphatic diester is methyl sebacate and the dihydroxy compound is ethylene glycol.

10. A process as defined in claim 7 wherein the aliphaticdiester is methyl sebacate and the dihydroxy compound is hexamethylene glycol.

11. A process as defined in claim 7 wherein the aliphatic diester is methyl adipate and the dihydroxy compound is hexamethylene glycol.

12. A process as defined in claim 7 wherein the aliphatic diester is ethyl succinate and the dihydroxy compound is tetramethylene glycol.

13. A process as defined in claim 1 wherein the sulfonyl dibenzoic diester is formed by a preliminary step comprising condensing p,p-sulfonyl dibenzoic acid with a dioxy compound which is defined under (B), at an elevated temperature, after which preliminary step the condensing agent which is defined under (C) is added and the condensation is completed as defined under (D), (E) and (F).

14. A process as defined in claim 13 wherein the preliminary elevated temperature is substantially that at which reflux conditions subsist, the subsequent condensation being conducted at a temperature which is gradually increased during the course of the condensation up to about 280-310 C, and the dioxy compound is employed in such proportion that there are from about 1.2 to about 3 oxy substituents in proportion to the carboxy and carbalkoxy substituents in the overall combination of the diacids, diesters and dioxy compounds.

15. A process as defined in claim 1 wherein the aliphatic diester is formed by a preliminary step comprising condensing an aliphatic acid selected from the group having the following formula:

wherein t represents a positive integer of from 2 to 18, with a dioxy compound which is defined under (H), at

an elevated temperature, after which preliminary step the condensing agent which is defined under (C) is added and the condensation is completed as defined under (D), (E) and ('F).

16. A process as defined in claim 15 wherein the preliminary elevated temperature is substantially that at which reflux conditions subsist, the subsequent condensation being conducted at a temperature which is gradually increased during the course of the condensation up to about 280310 C., and the dioxy compound is employed in such a proportion that there are from about 1.2 to about 3 oxy substituents in proportion to the carboxy and carbalkoxy substituents in the overall combination.

of the diacids, diesters and dioxy compounds. I

17. A process as defined in claim 16 wherein the condensing agent is employed in an amount of from about 0.005% to about 0.2% based on the weight of the diesters being condensed, the elevated temperature employed during the earlier part of the condensation to form the interpolyester is from about 150 C. to about 220 C.

and the low pressure defined under (F) is less than about 15 mm. of Hg pressure.

18. A linear interpolyester softening at above 180- 200 C. and having a softening temperature diiferential of from about 5 to 20 C. consisting of a ratio of about 10 of the following repeating units:

to each 1 up to 7 of one of the following repeating units:

-O-O C- (CH2) t-COO(C-H2) v wherein t represents a positive integer of from 2 to 18 and 1 represents a positive integer of from 2 to 1 2, which interpolyester has a low modulus of elasticity and is capable of being readily formed into shaped objects within its softening range, and wherein the -(CH2) units in the molecular structure include a substantial proportion of such units wherein p is at least 4.

14 19. A linear interpolyester as define-d in claim 18 wherein at least one of the repeating units depictedtherein is replaced by a member selected from the group consisting of the following repeating units corresponding thereto:

wherein it represents a positive integer of from 2 to 18, R7 represents an alkylene radical containing from 2 to 4 carbon atoms and q represents a positive integer of from 1 to 10. V

'20. A linear interpolyester as wherein p is 5 and t is 2.

defined in claim 18 wherein p is 4 and t is 2.

References Cited in the file of this patent UNITED STATES PATENTS 2,437,046 Rothrock et al Mar. 2, 194 8 2,465,319 Whinfield et a] Mar. 22, 1949 2,547,113 Drewitt et 'al. Apr. 3, 1951 2,623,033 Snyder Dec. 23, 1953 FOREIGN PATENTS 621,997 Great Britain Apr. 25, 1949 

1. A PROCESS FOR PREPARING A LINEAR POLYESTER SOFTENING AT ABOVE 18*-200* C. COMPRISING (A) CONDENSING ABOUT 10 MOLE PRPORTIONS OF OF A P,P''-SULFONYL DIBENOIC DIESTER HAVING FORMULA: 